JP4438808B2 - Conductive roll - Google Patents

Description

  The present invention relates to a conductive roll, and more particularly, to a conductive roll suitably used for an electrophotographic apparatus or the like.

  In recent years, electrophotographic apparatuses such as copying machines, printers, and facsimiles that employ an electrophotographic system have been widely used. A photosensitive drum is incorporated in this type of electrophotographic apparatus, and conductive rolls such as a developing roll, a charging roll, a transfer roll, and a toner supply roll are disposed around the photosensitive drum.

  In general, the conductive roll needs to have releasability with respect to toner. For this reason, a resin layer such as a fluororesin or a silicone resin that hardly adheres to the toner is often formed on the outermost periphery of the roll.

  In addition, an attempt has been made to impart releasability to the toner by forming the outermost roll periphery as a rubber layer and surface-treating the surface of the rubber layer without forming the resin layer.

  For example, Patent Document 1 discloses a roll for electrophotographic equipment in which a fluorine compound is chemically bonded to the rubber layer surface on the outermost periphery of the roll by atmospheric pressure plasma.

  By the way, as a rubber surface treatment method, for example, in Patent Document 2, the rubber surface is treated with fluorine gas in the presence of oxygen gas, an oxygen generating compound or an oxygen-containing compound having a vapor pressure of 1 torr or higher at 200 ° C. A method is disclosed.

  Patent Document 3 discloses a method in which a fluorine compound containing a fluoroalkyl group and a silane coupling agent are applied to the surface of a crosslinked rubber and then heat-treated. According to this method, it is said that the fluorine treatment effect can be stably exhibited even when it comes into contact with a solvent.

  Further, Patent Document 4 discloses a method of forming a treatment layer on a rubber surface using a treatment liquid containing a fluoro compound containing a fluoroalkyl group and a polyfunctional alkoxysilane. According to this method, it is said that antifouling properties can be imparted to the rubber surface.

JP 2003-165857 A JP 58-199132 A JP 2004-67882 A JP 2003-253022 A

  However, conventionally known conductive rolls have the following problems.

  That is, when the resin layer is formed on the outermost periphery of the roll, the flexibility and surface characteristics such as electric resistance are easily changed as compared with the roll surface layer before the resin layer is formed.

  For example, when the roll surface layer before forming the resin layer is a rubber layer, the resin layer is harder than the rubber layer, so that the flexibility of the rubber layer is impaired. For this reason, the resin layer may damage the photosensitive drum as the counterpart material or deteriorate the toner due to long-term use. Moreover, regardless of the case where the roll surface layer before forming the resin layer is a rubber layer, the electrical response is changed by forming the resin layer. As a result, there has been a problem that an image of the electrophotographic apparatus is defective.

  In addition, it is difficult to achieve both toner releasability and charging performance with the roll for electrophotographic equipment described in Patent Document 1 and the conventional conductive roll surface-treated with a fluorine additive. There was a problem.

  That is, when the roll is surface-treated by the method described in Patent Document 1 or the roll is surface-treated using a fluorine additive, the toner releasability on the roll surface is ensured. On the other hand, for example, when the conductive roll is a developing roll, the toner is difficult to be negatively charged. For example, when the conductive roll is a charged roll, the photosensitive drum is rubbed with the photosensitive drum. The charging performance deteriorates, for example, the positive charge is easily stored on the photosensitive drum. As described above, when the charging performance is deteriorated, image defects such as a decrease in image density and generation of horizontal streak images are likely to occur.

  This is because, when the roll is surface-treated with a fluorine additive, only electron-attracting fluorine atoms appear on the roll surface. For example, in the case of a developing roll, it becomes difficult to give electrons to the toner. In the case of a roll, when the photosensitive drum is subjected to a strong impact during transportation of the toner cartridge and the photosensitive drum is rubbed with the charging roll, positive charges are easily stored on the photosensitive drum due to the electron attractive property of fluorine atoms. It is guessed.

  The problem to be solved by the present invention is to provide a conductive roll that is less prone to image defects over a long period of time and is excellent in toner releasability and charging performance.

  In order to solve the above problems, the conductive roll according to the present invention includes an outermost layer containing an organic polymer on the outermost periphery of the roll, and the surface of the outermost layer has an F of 8 atomic% or more and O: 25. The gist is to have at least atomic percent.

  In this case, the atomic ratio of the oxygen atom to the fluorine atom is preferably in the range of 1.5 to 11.5.

At this time, it is desirable that the organic polymer in at least the surface portion of the outermost layer has a structure represented by the formula (1).

Then, the conductive roller, said the surface of the outermost layer may be obtained by contacting the mixed gas containing the F ₂ gas and O ₂ gas.

  The conductive roll according to the present invention has a specific amount of fluorine atoms and a specific amount of oxygen atoms on the surface of a roll outermost layer containing an organic polymer. Therefore, it is excellent in toner releasability and charging performance.

  This is because the presence of a specific amount of oxygen atoms together with a specific amount of fluorine atoms on the surface of the outermost layer of the roll makes it easier to give electrons to the toner, for example, in the case of a developing roll, and the toner chargeability is improved. It is presumed that. In addition, for example, in the case of a charging roll, it is presumed that positive charges are not easily stored on the photosensitive drum. As a result, the image quality can be improved.

  Moreover, the electroconductive roll which concerns on this invention modifies the surface of a roll outermost layer on a molecular level. Therefore, the toner releasability and charging performance are improved while maintaining the original flexibility and electrical resistance of the outermost roll layer. As a result, the stress on the photosensitive drum or toner, which is the counterpart material, is greatly reduced, and the reduction in electrical response is reduced.

  In this case, when the atomic ratio of the oxygen atom to the fluorine atom is in the range of 1.5 to 11.5, the above effect is further improved.

  At this time, when the organic polymer in at least the surface portion of the outermost layer has a structure represented by the above formula (1), the above effect is further improved.

The conductive roll according to the present invention, the surface of the roll outermost layer containing an organic polymer may be obtained by contacting the mixed gas containing the F ₂ gas and O ₂ gas. Therefore, a specific amount of fluorine atoms and a specific amount of oxygen atoms can be present on the surface of the roll outermost layer. Thereby, it is excellent in toner releasability and charging performance while maintaining the original flexibility and electrical resistance of the outermost layer of the roll.

Further, the F ₂ gas used for modifying the surface of the outermost roll layer is more reactive than conventional fluorine additives. Therefore, the organic polymer material used for forming the outermost roll layer is not easily limited, and it becomes possible to form the outermost roll layer using various organic polymers and modify it.

  Next, the conductive roll according to the embodiment of the present invention (hereinafter sometimes referred to as “main roll”) will be described in detail.

  This roll includes an outermost layer containing an organic polymer on the outermost periphery of the roll, and the surface of the outermost layer has a specific amount of fluorine atoms and a specific amount of oxygen atoms.

  One or two or more elastic layers may or may not be provided inside the outermost layer. That is, this roll should just consist of 1 layer or 2 layers or more including the said outermost layer.

  The outermost layer may be formed thick enough to form a roll body or may be formed in a thin film. The thicknesses of the outermost layer and the elastic layer can be appropriately selected in consideration of the use of the present roll, the installation space inside the electrophotographic apparatus incorporating the present roll, the type of the electrophotographic apparatus, and the like.

  In the present roll, the outermost layer preferably contains an organic polymer mainly. Examples of the organic polymer include rubber, thermoplastic elastomer, and resin. The organic polymer may or may not contain an unsaturated bond.

  Examples of the rubber include acrylonitrile-butadiene rubber (NBR), hydrogenated acrylonitrile-butadiene rubber (H-NBR), butadiene rubber (BR), isoprene rubber (IR), styrene-butadiene rubber (SBR), epichlorohydrin rubber ( Examples include ECO), acrylic rubber, chloroprene rubber (CR), butyl rubber, ethylene / propylene rubber, ethylene-propylene-diene rubber (EPDM), silicone rubber, urethane rubber, and natural rubber.

  Of these, acrylonitrile-butadiene rubber (NBR), butadiene rubber (BR), styrene-butadiene rubber (SBR), epichlorohydrin rubber (ECO), acrylic rubber, urethane rubber, and the like are preferable.

  Examples of the thermoplastic elastomer include styrene thermoplastic elastomer (SBC), olefin thermoplastic elastomer (TPO), urethane thermoplastic elastomer, polyester thermoplastic elastomer, polyamide thermoplastic elastomer (TPAE), and vinyl chloride. Thermoplastic elastomer (TPVC), nitrile thermoplastic elastomer, fluorine thermoplastic elastomer, chlorinated polyethylene (CPE), 1,2-polybutadiene, trans 1,4-polyisoprene, silicone thermoplastic elastomer, chlorinated ethylene copolymer Examples include crosslinked alloy, ester halogen-based polymer alloy and the like.

  Of these, olefin-based thermoplastic elastomers (TPO), urethane-based thermoplastic elastomers, polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers (TPAE), and nitrile-based thermoplastic elastomers are preferable.

  Examples of the resin include polyethylene, ultrahigh molecular weight polyethylene, polypropylene, polystyrene, polymethyl methacrylate, acrylonitrile-butadiene-styrene resin, polyvinyl chloride, polyurethane, polyamide, aromatic polyamide, monomer cast nylon, polyoxymethylene, Polycarbonate, polybutylene terephthalate, polyphenylene ether, polyethylene terephthalate, polyarylate, polysulfone, polyphenylene sulfide, polyether ketone, polyether imide, polyamide imide, polyether sulfone, liquid crystal polymer, polyether ether ketone, polyimide, polybenzimidazole, poly Tetrafluoroethylene, tetrafluoroethylene, polychlorotrifluoroethylene, te La fluoroethylene - ethylene copolymer, tetrafluoroethylene - hexafluoropropylene copolymer, polyvinylidene fluoride, epoxy resin, silicone resin, unsaturated polyester, phenolic resin, and the like can be exemplified acrylic resin. These resin materials are preferably rich in elasticity.

  Of these, acrylic resin, polyurethane, polyamide, polycarbonate, polyetherimide, polyamideimide, polyethersulfone, epoxy resin, unsaturated polyester, and the like are preferable.

  The outermost layer may include one or more of the rubber, the thermoplastic elastomer, and the resin. The combination of two or more may be two or more of the rubbers, two or more of the thermoplastic elastomers, or two or more of the resins, or the rubber, the heat Two or more kinds selected from a plastic elastomer and the above resin may be used.

  In the outermost layer, a conductive agent, a filler, an extender, a reinforcing agent, an activator, a processing aid, a vulcanization accelerator, a vulcanizing agent, an antioxidant, a plasticizer, a colorant, One or more additives such as an ultraviolet absorber and a foaming agent may be contained.

  Among these additives, examples of the conductive agent include electronic conductive agents such as carbon black, metal, and metal oxide, and ionic conductive agents such as quaternary ammonium salts. The type of conductive agent to be added and the amount of the conductive agent to be added may be appropriately selected in order to adjust the volume resistance or the like according to the member used such as a developing roll or a charging roll.

  As the proportion of the additive, conventionally known blending proportions can be appropriately adopted so that various additives can achieve their purpose.

  When the elastic layer is provided in the lower layer of the outermost layer, the material of the elastic layer is not particularly limited. For example, any kind of the organic polymer containing any kind of the additive in any amount can be exemplified. When a plurality of elastic layers are provided, each elastic layer may be the same material / composition, or may be a different material / composition.

  Here, the surface of the outermost layer preferably has 8 atomic% or more of fluorine atoms and 25 atomic% or more of oxygen atoms.

  The reason why a specific amount of fluorine atoms is present on the surface of the outermost layer is to improve the toner releasability of the roll by covering the surface with fluorine atoms. In addition, the presence of a specific amount of oxygen atoms together with fluorine atoms is because, for example, when the main roll is a developing roll, it is easy to give electrons to the toner, and the toner chargeability of the main roll is improved along with the toner releasability. Because.

  That is, since fluorine atoms have high electron withdrawing properties, if fluorine atoms are present on the surface, it becomes difficult to give electrons to the toner. For this reason, the presence of oxygen atoms on the surface opposite to the chargeability of fluorine atoms solves the problem that it is difficult to give electrons to the toner and makes it easier to charge the toner negatively.

  Further, for example, when the main roll is a charging roll, it is difficult to store positive charges on the photosensitive drum. In other words, the presence of oxygen atoms on the surface opposite to the fluorine atoms makes it possible to attract the fluorine atoms when the photosensitive drum is rubbed with the charging roll when subjected to a strong impact when the toner cartridge is transported. This is to prevent positive charges from being stored on the photosensitive drum due to the property.

  The reason why the surface atomic weight is defined as described above is that when the fluorine atom is less than 8 atomic%, the amount of fluorine atom on the surface of the outermost layer of the roll is small, so that the toner releasability of the roll tends to be lowered. It is. On the other hand, when the oxygen atom is less than 25 atomic%, the amount of oxygen atom on the surface of the outermost roll layer is small, so that it is easy to give electrons to the toner, and the effect of suppressing positive charge from being stored on the photosensitive drum. It is because it becomes easy to fall.

  On the other hand, on the surface of the outermost layer, the upper limit of the fluorine atomic weight is preferably 30 atomic% or less. This is because if it exceeds 30 atomic%, the toner is difficult to be negatively charged. This is also because positive charges are easily stored on the photosensitive drum. More preferably, it is 25 atomic% or less. Moreover, as an upper limit of oxygen atomic weight, it is preferable to set it as 50 atomic% or less. This is because if it exceeds 50 atomic%, the toner releasability tends to be lowered. More preferably, it is 45 atomic% or less.

  Under the present circumstances, it is preferable that the atomic ratio of the oxygen atom with respect to a fluorine atom exists in the range of 1.5-11.5. This is because both toner releasability and charging performance are easily improved. More preferably, the lower limit is that the atomic ratio is 1.5, and the upper limit is that the atomic ratio is 3.6.

  The surface composition of this roll can be analyzed by X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), or the like.

In this roll, in order to allow a specific amount of fluorine atoms and a specific amount of oxygen atoms to exist on the surface of the outermost layer, for example, a mixture containing F ₂ gas and O ₂ gas on the surface of the outermost layer. It is good to make gas contact.

In order to bring the mixed gas into contact with the surface of the outermost layer, a mixed gas containing F ₂ gas and O ₂ gas is placed in the processing container with the roll having the outermost layer placed in the processing container. The gas containing O ₂ gas and the gas containing F ₂ gas may be introduced separately. That is, it is only necessary to be in contact with a mixed gas containing F ₂ gas and O ₂ gas during the surface treatment. Inert gas such as N ₂ gas, Ar gas, and He gas is diluted in mixed gas containing F ₂ gas and O ₂ gas, gas containing O ₂ gas, and gas containing F ₂ gas It may be included as a gas.

  The processing container into which the gas is introduced may be hermetically sealed or non-sealed. Gas may be introduced into the sealed processing container in any state of normal pressure, reduced pressure, and increased pressure, and any state of normal pressure, reduced pressure, and increased pressure is introduced by introducing the gas. May be. The non-sealed processing container can be brought into contact with the above mixed gas while flowing.

In the mixed gas brought into contact with the surface of the outermost layer, the F ₂ gas concentration is preferably 3 vol% or more, more preferably 5 vol% or more as a lower limit. This is because a specific amount of fluorine atoms can surely exist on the surface of the outermost layer. On the other hand, the upper limit is preferably 50 vol% or less, more preferably 30 vol% or less, from the viewpoint of handling safety.

The lower limit of the O ₂ gas concentration is preferably 20 vol% or more, more preferably 30 vol% or more. This is because a specific amount of oxygen atoms can surely exist on the surface of the outermost layer. On the other hand, the upper limit is preferably 97 vol% or less, more preferably 95 vol% or less, because of the necessity of the presence of F ₂ gas.

In the mixed gas, it is not particularly limited amount of O ₂ gas to the F ₂ gas, preferably, may F ₂ amount of O ₂ gas is greater than the gas. This is because the surface O concentration becomes higher than that of the conventional conductive roll by allowing the O ₂ gas to be present at a high concentration together with the F ₂ gas. Thus, by increasing the surface O concentration, the effect of further improving the charging performance can be exhibited while ensuring the toner releasability of the roll.

In this case, the preferred range of the volume ratio of _{O 2} gas to the _{F 2} gas, the upper limit value, for example, can be exemplified a 98/2, 95 / 5,90 / 10. On the other hand, examples of the lower limit value that can be combined with the upper limit value include 70/30, 60/40, and 55/45.

  The treatment of bringing the mixed gas into contact with the surface of the outermost layer can basically be performed at around room temperature, but the treatment temperature may be appropriately adjusted as necessary. Specifically, for example, the temperature is preferably in the range of 0 to 200 ° C. More preferably, it is in the range of room temperature to 100 ° C. More preferably, it is in the range of room temperature to 60 ° C. In addition, when process temperature is made too high, the tendency of surface property deterioration, such as a crack arising in the surface, is seen. Therefore, it is preferable to select the processing temperature with this point in mind.

At this time, the treatment time can be appropriately selected within a range of 1 second to several days, although it varies depending on the F ₂ gas concentration and the O ₂ gas concentration in the mixed gas. However, when the treatment time is excessively long, there is a tendency for the production efficiency of the roll to decrease. On the other hand, when the treatment time is excessively short, there is a tendency that the reaction with the organic polymer on the surface of the outermost layer becomes insufficient. Therefore, it is preferable to select the processing time in consideration of these. Considering productivity and reactivity, it is preferably in the range of 1 minute to several hours. More preferably, it is in the range of 1 minute to 1 hour.

The present roll treated with a mixed gas containing F ₂ gas and O ₂ gas has fluorine atoms and oxygen atoms in various bond forms on the surface of the outermost layer. At this time, the organic polymer in at least the surface portion of the outermost layer containing the organic polymer preferably has a carbon-fluorine bond or a carbon-oxygen bond. Further, in the present roll, it is particularly preferable that at least the organic polymer in the surface portion has a structure represented by the following formula (1).

The structure represented by the above formula (1) is particularly easily formed when the roll outermost layer is treated with a mixed gas containing F ₂ gas and O ₂ gas. That is, it is easy to infer that the roll having the structure shown in the above (1) is obtained by treating the outermost layer of the roll with a mixed gas containing F ₂ gas and O ₂ gas.

  The organic polymer of the surface part and other parts has a carbon-fluorine bond, a carbon-oxygen bond, or a structure represented by the above formula (1), This can be confirmed by analysis by X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), or the like.

  The structure shown in the above formula (1) may exist not only in the surface portion of the outermost roll layer but also in the outermost roll layer. In this case, the existence state of the structure is not particularly limited. For example, the structure may be distributed in an inclined manner so that the existence ratio of the structure decreases or increases from the outermost layer surface to the inside, or at almost the same existence ratio over a certain distance from the outermost layer surface to the inside. It may be distributed.

  The main roll described above can be suitably used as a conductive roll such as a developing roll such as an electrophotographic apparatus, a charging roll, a toner supply roll, and a transfer roll.

  In this roll, a known method can be used as a method of forming the outermost layer before contacting the mixed gas. For example, a method of extruding the above-described organic polymer material on the surface of a conductive shaft optionally coated with a primer such as an adhesive, and the above-described organic polymer material is injected into a mold in which the conductive shaft is set. Examples of the method include demolding after heating and vulcanization.

  At this time, when an elastic layer is formed in the lowermost layer of the outermost layer, one or more elastic layer materials described above are extruded or injection-molded on the outer periphery of the conductive shaft, and then the outermost elastic layer surface is formed. In addition, an organic polymer material may be applied by a roll coating method, a dipping coating method, a spray coating method, or the like, dried, and crosslinked.

  The outermost layer may be treated with a fluorine additive or the like before being surface-treated with the mixed gas.

  Examples of the fluorine additive include a fluorine compound containing a fluoro group or a fluoroalkyl group and a silanol group, and a fluorine compound containing a fluoro group or a fluoroalkyl group and an acrylic group.

  Specifically, for example, “Megafac F-443” manufactured by Dainippon Ink & Chemicals, Inc., “Modiper F-600” manufactured by Nippon Oil & Fats can be exemplified.

  The fluorine additive may be used as it is, or may be used in the form of a solution by dissolving in a solvent or the like. The concentration in the case of a solution can be appropriately selected in consideration of the amount added and ease of handling. As a method of surface treatment, a method of immersing the outermost layer in a fluorine additive or a solution containing the same, a method of mixing or coating or spraying a fluorine additive or a solution containing the same with a paint forming the outermost layer, etc. Can be used. Furthermore, the treatment temperature can be set to room temperature or a suitable temperature according to the properties of the fluorine additive, and can be appropriately selected.

  Hereinafter, the present invention will be described in detail using examples. Hereinafter, the case where the present invention is applied to a developing roll and a charging roll will be exemplified.

<Development roll>
(Preparation of rubber composition)
100 parts by weight of nitrile rubber (NBR) (manufactured by Zeon Corporation, “Nipol DN401”), 0.5 parts by weight of stearic acid (manufactured by Kao Corporation, “Lunac S-30”), carbon black (Cabot 40 parts by weight of “Show Black N220” manufactured by Japan Co., Ltd., 5 parts by weight of zinc oxide (ZnO), and sulfenamide-based vulcanization accelerator (manufactured by Ouchi Shinsei Chemical Co., Ltd., “Noxeller CZ-G”) ") 1 part by weight, dithiocarbamate vulcanization accelerator (Ouchi Shinsei Chemical Co., Ltd.," Noxeller BZ-P ") 0.5 part by weight, powdered sulfur 1 part by weight, rubber with a kneader By kneading, a rubber composition <1> was prepared.

(Preparation of surface coating)
100 parts by weight of acrylic rubber (manufactured by Nippon Zeon Co., Ltd., “NIPOL AR32”), 20 parts by weight of carbon black (manufactured by Mitsubishi Chemical Corporation, “MA-220”), and 880 parts by weight of methyl ethyl ketone (MEK) The surface coating material <1> was prepared by kneading using a roll.

  100 parts by weight of urethane elastomer (manufactured by Nippon Polyurethane Industry Co., Ltd., “Milactolan XN-2001”), 20 parts by weight of carbon black (manufactured by Mitsubishi Chemical Co., Ltd., “MA-220”), and 880 weights of methyl ethyl ketone (MEK) Part was kneaded using a roll to prepare surface coating <2>.

  In the preparation of the surface coating material <1>, except that 3 parts by weight of a fluorine additive (“Megafac F-443” manufactured by Dainippon Ink & Chemicals, Inc.) was further added, Surface coating <3> was prepared in the same manner as the preparation.

  In the preparation of the above surface coating <1>, the surface coating <1 except that 0.5 parts by weight of a fluorine additive (“Megafac F-443” manufactured by Dainippon Ink & Chemicals, Inc.) was further added. > The surface coating material <4> was prepared in the same manner as the preparation of>.

  In the preparation of the surface coating material <1>, except that 1 part by weight of a fluorine additive (“Megafac F-443” manufactured by Dainippon Ink and Chemicals, Inc.) was further added, Surface coating <5> was prepared in the same manner as the preparation.

(Preparation of developing roll)
(Example 1G)
After setting a metal shaft (diameter 6 mm) coated with an adhesive in the mold, the rubber composition <1> is injected into the mold, heated at 160 ° C. for 30 minutes and cured, and then demolded. Then, one rubber layer (thickness 4 mm) was formed on the outer periphery of the conductive shaft. Next, the surface layer paint <1> was applied on the rubber layer and dried at 120 ° C. for 30 minutes to prepare a roll body having a surface layer (thickness 20 μm).

Next, the roll body was placed in a hermetically sealed processing container, and the processing container was depressurized to several hundred Pa or less, and then nitrogen gas was introduced to replace the gas in the processing container. Thereafter, under the condition of 25 ° C., the gas is introduced so that the gas mixing ratio in the processing container becomes the F ₂ gas concentration of 20 vol% and the O ₂ gas concentration of 80 vol%. Touched for a minute. Next, the unreacted mixed gas was discharged from the processing container and taken out from the processing container to produce a developing roll according to Example 1G.

(Examples 2G-7G)
Under the respective processing conditions shown in Table 1, in the same manner as in Example 1G, a mixed gas was brought into contact with the roll body to produce developing rolls according to Examples 2G to 7G.

(Example 8G)
In preparing the roll body of Example 1G, a roll body was prepared in the same manner as in Example 1G, except that the surface layer paint <3> was used instead of the surface layer paint <1>. Thereafter, a mixed roll was brought into contact with the roll body under the processing conditions shown in Table 1 in the same manner as in Example 1G to produce a developing roll according to Example 8G.
(Example 9G)
In the preparation of the roll body of Example 1G, a roll body was prepared in the same manner as in Example 1G, except that the surface layer paint was not applied on the rubber layer. Thereafter, under the processing conditions shown in Table 1, a mixed gas was brought into contact with the roll body in the same manner as in Example 1G to produce a developing roll according to Example 9G.

(Example 10G)
In preparing the roll body of Example 1G, a roll body was prepared in the same manner as in Example 1G, except that the surface layer paint <2> was used instead of the surface layer paint <1>. Thereafter, under the processing conditions shown in Table 1, a mixed gas was brought into contact with the roll body in the same manner as in Example 1G to produce a developing roll according to Example 10G.

(Comparative Example 1G)
In Example 1G, the developing roll according to Comparative Example 1G was prepared in the same manner as Example 1G, except that a mixed gas not containing O ₂ gas (mixed gas of F ₂ gas and N ₂ gas) was contacted. Produced.

(Comparative Example 2G)
A developing roll according to Comparative Example 2G was produced in the same manner as in Example 1G, except that in Example 1G, a mixed gas having a low F ₂ gas concentration was contacted.

(Comparative Example 3G)
In Example 1G, a developing roll according to Comparative Example 3G was produced in the same manner as Example 1G, except that the mixed gas containing F ₂ gas and O ₂ gas was not brought into contact.

(Comparative Example 4G)
In preparing the roll body of Example 1G, a roll body was prepared in the same manner as in Example 1G, except that the surface layer paint <4> was used instead of the surface layer paint <1>. Thereafter, a developing roll according to Comparative Example 4G was obtained without introducing a mixed gas containing F ₂ gas and O ₂ gas.

(Comparative Example 5G)
In the preparation of the roll body of Example 1G, a roll body was prepared in the same manner as in Example 1G, except that the surface layer paint <5> was used instead of the surface layer paint <1>. Thereafter, a developing roll according to Comparative Example 5G was obtained without introducing a mixed gas containing F ₂ gas and O ₂ gas.

(Comparative Example 6G)
In preparing the roll body of Example 1G, a roll body was prepared in the same manner as in Example 1G, except that the surface layer paint <3> was used instead of the surface layer paint <1>. Thereafter, a developing roll according to Comparative Example 6G was obtained without introducing a mixed gas containing F ₂ gas and O ₂ gas.

(Comparative Example 7G)
In Example 9G, a developing roll according to Comparative Example 7G was produced in the same manner as Example 9G, except that the mixed gas containing F ₂ gas and O ₂ gas was not contacted.

(Comparative Example 8G)
In Example 10G, a developing roll according to Comparative Example 8G was produced in the same manner as Example 10G, except that the mixed gas containing F ₂ gas and O ₂ gas was not contacted.

(Surface structure of developing roll according to example)
About the developing roll which concerns on each produced said Example, the surface structure was investigated by XPS and IR. As a result, it was confirmed that the organic polymer (rubber, resin) in the surface portion of the developing roll according to any of the examples had the structure of the above formula (1).

(Evaluation of each developing roll)
The following six items were evaluated for each developing roll according to Examples and Comparative Examples.

<Measurement of surface atom concentration>
Using an ESCA system (PHI5600 system, manufactured by ULVAC-PHI), the surface F concentration and surface O concentration of each developing roll were measured under the following measurement conditions. That is, while irradiating with X-rays using an Al monochromator (14 kV, 150 W) and correcting for charging with an electron neutralizing gun, measurement area: φ800 μm, photoelectron extraction angle: 45 deg, resolution 187.85 passenery, 0.8 eV The measurement was performed under the conditions of / step and 20 time / step.

<Toner chargeability>
Each developing roll is incorporated into a commercially available color laser printer ("LBP-2510" manufactured by Canon Inc.), and the toner charge amount on the roll after 10 rotations of the developing roll is measured in an environment of 20 ° C x 50% RH. It was measured. In the printer, the toner thinning blade was made of urethane rubber, the toner supply roll was made of conductive urethane sponge, and the toner was negatively charged toner.

<Image density>
Each developing roll is incorporated in a commercially available color laser printer (manufactured by Canon Inc., “LBP-2510”), and images are taken out in an environment of 20 ° C. × 50% RH, and the density in a solid black image is set to the Macbeth density. Measured using a meter. As a result, those having a density of 1.2 or more were accepted. Among these, those with 1.2 to 1.4 were evaluated as good “◯”, and those exceeding 1.4 were evaluated as “Excellent”. On the other hand, a sample having a density of less than 1.2 was regarded as “failed”.

<Toner adhesion after endurance>
Each developing roll is incorporated into a commercially available color laser printer (manufactured by Canon Inc., “LBP-2510”), and under an environment of 20 ° C. × 50% RH, 1000 images (A4 size) are printed. The subsequent roller appearance was confirmed. That is, after the durability evaluation, the case where there was no image disturbance was regarded as acceptable. Among these, the case where the toner is hardly present on the roll surface was particularly marked “◎”, and the case where the toner slightly adhered on the roll surface was rated “good”. On the other hand, when toner adheres on the surface of the roll and uneven adhesion occurs on the image, it is determined as “Fail”.

<Uneven density>
Each developing roll was incorporated into a commercially available color laser printer ("LBP-2510" manufactured by Canon Inc.), and after image formation was performed in an environment of 20 ° C x 50% RH, the copy image quality was evaluated. . As a result, a sample in which density unevenness in a halftone image did not occur was determined to be acceptable. Among these, thin line breaks, color irregularities, and those that did not have streak images were particularly excellent `` ◎ '', fine line breaks, color irregularities, streak images were slightly produced but density irregularities did not occur `` Good ''" On the other hand, the case where density unevenness occurred was regarded as a failure “x”.

<Roll surface hardness>
As reference data, the surface hardness of each developing roll was measured with an MD-1 hardness meter (manufactured by Kobunshi Keiki Co., Ltd., “Micro rubber hardness meter MD-1 type”) (N = 3).

  Table 1 below summarizes the evaluation results.

  According to Table 1, all of the developing rolls according to Comparative Examples 1G to 8G have a low toner chargeability, resulting in a low image density and a defective image, or a large amount of toner after durability. It turns out that it is inferior to mold release property.

Specifically, in Comparative Example 1G, since the mixed gas brought into contact with the surface of the roll body does not contain O ₂ gas, the surface O concentration of the developing roll is low. Therefore, the toner chargeability is lowered and the image density is inferior. In Comparative Example 2G, since the F ₂ gas concentration in the mixed gas brought into contact with the surface of the roll body is low, the surface F concentration of the developing roll is low. Therefore, the toner adhesion after durability is inferior (toner adhesion is large) and the toner releasability is inferior.

In Comparative Examples 3G, 7G, and 8G, since the surface of the roll body is not surface-treated with F ₂ gas or a fluorine additive, there are no F atoms on the surface of the developing roll. Therefore, the toner adhesion after durability is inferior and the toner releasability is inferior. In Comparative Example 4G, the surface of the roll body is surface-treated with a fluorine additive, but the surface F concentration of the developing roll is low because the amount of the fluorine additive is small. Therefore, the toner adhesion after durability is inferior and the toner releasability is inferior.

  In Comparative Examples 5G and 6G, the surface of the roll body is surface-treated with a fluorine additive, and the surface F concentration of the developing roll is relatively high, but the surface O concentration is low. Therefore, the toner chargeability is lowered and the image density is inferior.

  On the other hand, all of the developing rolls according to Examples 1G to 10G are excellent in toner releasability and toner chargeability because the surface F concentration and the surface O concentration are in the specific range. Yes. For this reason, it was confirmed that the image density was excellent, there was almost no toner adhesion after durability, and no image unevenness occurred.

  In addition, since the developing rolls according to Examples 1G to 10G do not have a resin layer such as a fluororesin that imparts toner releasability on the surface, images resulting from peeling or cracking of the resin layer. It can be said that defects do not easily occur.

  Furthermore, the developing rolls according to Examples 1G to 10G modify the roll surface at the molecular level. Therefore, characteristics such as the original flexibility and electrical resistance of the roll surface can be maintained. As a result, the stress on the photosensitive drum and toner as the counterpart material can be greatly reduced. In addition, since the decrease in electrical response is reduced, the repetition rate of charge removal and discharge is faster compared to conventional products with a resin layer such as a fluororesin on the surface, and the ability to impart charge or charge toner. The improvement of sex can also be expected.

<Charging roll>
(Preparation of rubber composition)
Epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer (manufactured by Daiso Corporation, "Epichromer CG-102") and stearic acid (Kao Corporation, "Lunac S-30") 1 part by weight, 1 part by weight of tributylethylammonium ethyl sulfate (quaternary ammonium salt), 5 parts by weight of zinc oxide (ZnO), 0.25 part by weight of sulfur, 1 part by weight of morpholine disulfide, and tetramethylthiuram A rubber composition <2> was prepared by kneading 1.2 parts by weight of disulfide with a kneader.

(Preparation of charging roll)
Examples 1T to 10T were the same as Examples 1G to 10G and Comparative Examples 1G to 8G, respectively, except that the rubber composition <1> was replaced with the rubber composition <2> in the production of the developing roll. The charging rolls according to Comparative Examples 1T to 8T were produced. In Example 9T and Comparative Example 7T, since the surface layer paint is not applied on the rubber layer, the roll surface base material is made of hydrin rubber of rubber composition <2>. Each processing condition is shown in Table 2.

(Surface structure of charging roll according to example)
About the charging roll which concerns on the produced said Example, the surface structure was measured by XPS and IR. As a result, it was confirmed that the organic polymer (rubber, resin) in the surface portion of the developing roll according to any of the examples had the structure of the above formula (1).

(Evaluation of each charging roll)
About each charging roll which concerns on an Example and a comparative example, the following 4 items were evaluated.

<Measurement of surface atom concentration>
The surface F concentration and surface O concentration of each charging roll were measured using an ESCA system (PHI5600 system, manufactured by ULVAC-PHI) in the same manner as when measuring the developing roll.

<Charging memory>
Each charging roll is assembled into a cartridge of a commercially available color laser printer (manufactured by Canon Inc., “LBP-2510”), and this cartridge is packed in a commercially available state (packed with a cushioning material on the cartridge and packed in cardboard) ) With this packing state, the operation of free-falling on the iron plate from a height of 1 m was repeated three times so that the axis of the charging roll was vertical. Immediately thereafter, this cartridge was incorporated into the printer, and a halftone image was taken out in an environment of 20 ° C. × 50% RH. When the image is visually confirmed, “◎” when the streak-like memory image is not seen, “○” when the streak-like memory image is slightly seen, and when the streak-like memory image can be clearly seen Was marked “x”.

<External additive adhesion>
Each of the obtained charging rolls was incorporated into a full color LBP, and after 10,000 images were printed (magenta halftone), the state of the printed image was visually evaluated and the contamination of the roll surface (toner external addition) The adhesion amount of the agent was visually evaluated. That is, even after 10,000 images have been printed, a print image that has no problem is regarded as acceptable. Among these, those that were clearly printed up to fine lines and that had almost no contamination on the roll surface were particularly excellent “◎”, and those that had no problem with the printed image were rated “good”. On the other hand, a print image in which density unevenness was observed and contamination of the roll surface was spread over the entire surface was determined as a failure “x”.

<Roll hardness>
As reference data, the surface hardness of each charging roll was measured (N = 3) with an MD-1 hardness meter (manufactured by Kobunshi Keiki Co., Ltd., “Micro rubber hardness meter MD-1 type”).

  Table 2 below summarizes the evaluation results.

  According to Table 2, in the charging rolls according to Comparative Examples 1T to 8T, the problem of image failure due to the charging memory occurs, or the problem of image failure due to the adhesion of the external toner additive occurs. It turns out that it is inferior.

Specifically, in Comparative Example 1T, a problem of image failure due to the charging memory occurred. This is because the O ₂ gas is not included in the mixed gas brought into contact with the surface of the roll body, so that the surface O concentration of the charging roll is not within a specific range. For this reason, it is considered that when the photosensitive drum is rubbed with the charging roll, positive charges are easily stored on the photosensitive drum due to the electron withdrawing property of fluorine on the surface of the charging roll.

In Comparative Example 2T, there was a problem of image failure due to adhesion of the toner external additive. This is because the F ₂ gas concentration in the mixed gas brought into contact with the surface of the roll body is low, so that the surface F concentration of the charging roll is not within a specific range. For this reason, it is considered that the toner external additive easily adheres to the surface of the charging roll.

In Comparative Examples 3T, 7T, and 8T, a problem of image failure due to adhesion of the toner external additive occurred. This is because the surface of the roll body is not surface-treated with F ₂ gas or a fluorine additive, and therefore F atoms are not present on the surface of the charging roll. For this reason, it is considered that the toner external additive easily adheres to the surface of the charging roll.

  In Comparative Examples 5T and 6T, a problem of image failure due to the charging memory occurred. This is because, as a result of the surface treatment of the roll body with the fluorine additive, the surface F concentration of the charging roll is within a specific range, but the surface O concentration is not within the specific range. For this reason, it is considered that when the photosensitive drum is rubbed with the charging roll, positive charges are easily stored on the photosensitive drum due to the electron withdrawing property of fluorine on the surface of the charging roll.

  On the other hand, in each of the charging rolls according to Examples 1T to 10T, the surface F concentration and the surface O concentration are in the specific range. Therefore, the problem of image failure due to the adhesion of the toner external additive and the problem of image failure due to the charging memory did not occur, and it was confirmed that the toner releasability and charging performance were excellent.

  Therefore, according to the charging rolls according to Examples 1T to 10T, the adhesion of the toner external additive to the charging roll is reduced, so that the problem of image defects due to this is less likely to occur. In addition, the photosensitive drum may be rubbed by the charging roll when it receives a strong impact during transportation of the toner cartridge. In such a case as well, positive charges are not easily stored on the photosensitive drum. The problem that a horizontal streak image occurs is less likely to occur.

  As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to the said Example at all, A various change is possible in the range which does not deviate from the summary of this invention.

Claims (4)

The outermost layer containing the organic polymer is provided on the outermost periphery of the roll,
The conductive roll characterized in that the surface of the outermost layer has F: 8 atomic% or more and O: 25 atomic% or more.   2. The conductive roll according to claim 1, wherein an atomic ratio of the oxygen atom to the fluorine atom is in a range of 1.5 to 11.5. The conductive roll according to claim 1 or 2, wherein the organic polymer in at least the surface portion of the outermost layer has a structure represented by the formula (1).

The outermost layer containing the organic polymer is provided on the outermost periphery of the roll,
4. The conductive roll according to claim 1, wherein the conductive roll can be obtained by bringing a mixed gas containing F ₂ gas and O ₂ gas into contact with the surface of the outermost layer. 5.